1. Field of the Invention
This invention relates to a machine, such as a differential pressure forming machine, having opposed die parts which are relatively movable between spaced apart positions and closed or "shut" positions for performing an operation, such as molding three dimensional articles in a sheet of thermoplastic material, and more particularly to adjustable eccentric mechanism for adjustably mounting the die parts in any selected one of a plurality of different positions to control the spacing between opposed die parts when the die parts are closed or "shut" while the machine is running.
2. Description of the Prior Art
Differential pressure forming machines, such as that disclosed in U.S. Pat. No. 3,346,923 issued to G. W. Brown, et al on Oct. 17, 1967, and U.S. Pat. No. 3,496,257 issued to G. W. Brown et al on Feb. 17, 1970, which are fully incorporated herein by reference as though recited word-for-word, include a pair of differential pressure molds which are vertically moved between spaced apart positions and closed adjacent positions abutting opposite sides of a thermoplastic sheet of material at a forming station to differential pressure form an object therein.
A thermoforming machine, such as that disclosed in U.S. Pat. No. 27,137 issued to G. W. Brown et al, on June 8, 1971, which is fully incorporated herein by reference a though recited word-for-word herein, also includes die parts which are mounted for movement between spaced apart positions and closed positions in engagement with opposite sides of a thermoplastic sheet to differentially pressure form three dimensional articles therein.
When the molds are moved to closed or "shut" molding positions, it is important that they be precisely positioned so as to be in sealing engagement with opposite sides of a heated sheet or web of thermoplastic material. The distance between the molds in the closed positions, is conventionally referred to as the "shut height". Due to varying thicknesses of sheets and also, because, after initial set-up, the molds frequently will be improperly set, when the molds close, they do not properly engage the sheet. Wear of moving parts will also sometimes vary the shut height after the machine has operated for a period of time. Thus, it is important that the shut height, distance or spacing between the molds in the closed molding positions be adjustable.
Such thermoforming machines typically include vertically movable upper and lower platens mounting upper and lower molds. Apparatus has been provided heretofore for vertically adjusting the position of the upper platen. One such prior art device included an adjustable eccentric mechanism for adjustably mounting the upper mold mounting platen. A thermoforming machine, such as that disclosed in U.S. Pat. No. 3,677,675 issued to Gaylord W. Brown on July 18, 1972, includes a differential pressure forming machine including apparatus for vertically moving the entire header which mounts the upper platen. Such prior art apparatus required that the machine be shut down including, disabling the heaters, prior to making the adjustments. Any such shut-down decreases operational efficiency and output of the machine.
Accordingly, it is an object of the present invention to provide new and novel apparatus for adjusting the shut height of a differential pressure thermoforming machine while the machine is operating.
It is another object of the present invention to provide new and novel apparatus for vertically adjusting the position of the lower platen in a differential pressure forming machine including upper and lower platens mounting upper and lower opposed molds.
It is yet another object of the present invention to provide new and novel apparatus for adjusting the shut height of a differential pressure forming machine while the machine is operating.
It is another object of the present invention to improve the operational efficiency of a differential pressure forming machine of the type described.
Still another object of the present invention is to provide a differential pressure forming machine including upper and lower mold members and mechanism for vertically adjusting the position of one of the mold members relative to the other mold members so that when the mold members are moved to closed positions, the mold members may be accurately and precisely positioned.
Apparatus, such as that disclosed in the referenced patents, includes pivotally coupled toggle links mounted between the frame and the mold mounting platens for locking the mold members in mold position in sealing engagement with the thermoplastic sheet of material.
Still another object of the present invention is to provide apparatus of the type described including shut height adjustment apparatus comprising cooperating wedge blocks which are relatively adjustable to control the position of the toggle links for the lower mold platen.
A still further object of the present invention is to provide apparatus of the type described including shut height adjustment mechanism having a wedge shaped, toggle link mounting block mounting a toggle link which locks the lower mold in the shut position and a cooperating wedge block for vertically adjusting the position of the toggle link mounting block.
It is another object of the present invention to provide a machine including die parts which move between spaced apart positions and closed positions engaging a sheet of thermoplastic material including cooperating wedge blocks which are laterally relatively adjustable to vertically adjust the machine.
Other objects and advantages of the present invention will become apparent to those of ordinary skill in the art as the description thereof proceeds.